In a disk drive, read offset correction or the like has been performed based on a situation of surrounding environment or a disk eccentricity amount. In the read offset correction, offset (read offset) at the time of reading data written on the disk is corrected.
However, although it is presumed for the read offset correction that write data are recorded correctly at a desired position, this is not guaranteed. For this reason, in a case where mechanical displacement occurs in the disk drive after shipment at a factory, there is a possibility that the data recorded after the occurrence of the mechanical displacement are recorded at a position different from a desired position. As a result, in the disk drive, it may occur that the data written on the disk are not correctly read.